An Unlikely Undercover Agent
by victoriadorian
Summary: Set after S3. Mycroft agrees to keep an eye on his little brother for the government. However, this proves harder than he first anticipates. What with John being occupied by the arrival of the baby- and himself lacking the usual sensitivity- Mycroft decides to hire a failing actress to play the perfect part. For Fith, everything changes. Especially with the return of Moriarty.


**The one where Mycroft hatches a terrible plan**

When Mycroft had first made contact with Fith, it seemed that he was successful in doing one thing: exasperating her, although she didn't think that that was his ultimate intention. Not at first, anyway. Later on during the course of their 'acquaintanceship', when he discovered the irksome effect he had, Mycroft had blamed it entirely on her, claiming that she was ' _close-minded'_ and _'too naive'_ when it came to _'great matters'_ , but she knew that, in reality, it was his methods of, uh, _communication_ that were at fault.

Back on that first fateful day, having just disrupted her Skype call to Luke- her boyfriend from America- in order to broadcast a live stream from his office, they had made their first (highly awkward) introductions. For Fith, it was traumatic. If given the choice between listening to Luke's loving words or taking part in a sharp conversation with a scowling stranger, equipped with a fancy looking umbrella, then it wouldn't have been difficult to decide. Unluckily for Fith, however, it wasn't her choice to make, it seemed.

It was awkward for a number of reasons, although neither would agree with the other about whose fault it was in particular. Fith did, however, have her reasons, and even Mycroft couldn't argue that hijacking a computer screen in a young woman's bedroom was not his greatest of plans.

When Russell, one of the young 'techies' hired, managed to fix his microphone, Mycroft's first words to Fith were, "Don't scream!" which, luckily for him, was just in time. Her face had been screwed up in a fearful expression and her mouth was opened wide enough to wail the place down, which is how her face remained until he was successful in assuring her that he wasn't, in fact, a pervert.

Her first impression of the man was that he didn't seem very comfortable with the level of technicality that went behind the process of hacking one's computer. The young enthusiasts he had hired to help him were certainly getting some colourful questions from the man, especially Russell, who appeared to be the mouthpiece for the nervous bunch. Mycroft, Fith had deduced, (a word newly added to her vocabulary, she would have you know; he used it several times throughout their conversation), was not a patient man. He did later admit to her, albeit reluctantly, that he prefers a more face-to-face approach when conducting business. This had been very obvious from the start.

So why had this man made his presence unexpectedly known to her? It took him a while to explain properly, and at first, Fith hadn't been listening. She was too busy complaining.

He would have said something first, but it was too late. By that point, the shock had worn off and was instead replaced with Fith's infamous words of fury. "What are you _doing_?" She had whispered furiously at the screen, careful so as not to alert her family's attention from downstairs, although she wondered if that would be a good idea in a situation like this. How would she know? It wasn't like having her laptop hacked was a usual occurrence in her life.

Mycroft had raised his hands, as if to calm her down, but it was useless. "Who are you?" She hissed, suspicion clearly painted across her face. The slight turn of her head, and the way she slowly reached for the phone behind her, had alerted Mycroft's attention.

He proclaimed in a rather pompous tone, "There's no need to phone the police. Just let me explain-"

Interrupting him, she cried, (albeit quietly), " _What?_ Are you telling me I-? I can phone them if I want to. Just watch-" From this, Mycroft would soon learn not to question Fith's ability to do something, it only spurred her on further. She was an extremely stubborn person to say the least.

"If you would just let me explain-"

Her faced dawned with horror. "Is my computer tagged?" She squeaked, looking at her once trusty friend with a newly found sense of suspicion. Aghast, she pushed herself away from it.

"Is it _what?_ "

"Is it tagged?" She repeated, now crawling back so she could hold a thorough search of her laptop, checking for any signs of misuse. It didn't look tampered with. Only a few dents and markings singled it as old, and even then that was just from late-night blogging with her clumsy genes, not from being in the grips of a psychopathic pervert.

Russell, with great trepidation, had approached the man, staring straight at the camera. "Excuse me, ma'am," he started anxiously, all too aware of the death glare he was receiving from Mycroft.

" _Ma'am_?" His use of this one certain word had put a stop to Fith's extensive search. Turning to face her computer's screen slowly, the two men looked uncomfortable as she squeaked in a dangerously low tone, "Who're you calling _ma'am_?"

"I just meant that-" Russell had stuttered, but soon gave up. "Your computer isn't, erm, tagged, as such. It hasn't been affected in any way from this, well, not technically, it's just that, erm, we've hijacked the waves being transmitted. It's easy, see, all we had to do was-"

"That's enough," The man had said in an icy tone. Russell had obeyed meekly, stepping back. Now directing his words to Fith herself, he said in a cool tone, "You will listen to me." And she did, although she didn't look too happy about it, instead rolling her eyes. "My name is Mycroft Holmes. I hold a minor position in the British Government, and I have plans that could, should you choose to accept," he began to twirl his umbrella in a dramatic motion before turning his attention back to Fith, "involve you."

As a result, she looked confused, and then suspicious again. "And why should I believe you?" She asked, her eyes glue to the screen of her computer. "For all I know you could be a psychopathic pervert with the intentions of trafficking me in a foreign country."

Mycroft had smiled coldly at this. "I can assure you that my position is genuine," was all the he said.

Fith wasn't having this, however. "But how do I know?" She repeated, putting emphasis on the word 'know'. "And what other kind of plans could you have for me? I'm hardly clever, nor do I possess any particular skills. I mean-" She froze, her eyebrows raised in astonishment. "Wait, are you recruiting me to _MI5_?"

"No," he said, giving her a strange look, "I'm not recruiting you to MI5."

She sighed at that, although a small part of her was relieved. To say that she was spy material would have been an extreme lie, and if he was in fact a part of the government then lying was a no-go area. Also, being a spy would mean a lot of training, which didn't excite her to say the least.

"But I am offering you the chance for espionage, should you, once again, choose to consent."

This left Fith speechless, something that Mycroft had noted with relief. As an unemployed, stay-at-home person whose biggest achievement was her long-term relationship and ability to cook some mean spaghetti sauce, things had taken a huge turn from her usual, mundane life.

"Excuse me," she eventually croaked, and those watching in Mycroft's office were surprised to watch Fith pinch herself, and then again, and then again, until she had left what would most certainly become a bruise the next day on her left arm.

She exhaled carefully a few times, using the same techniques that she had learned when her friend (who had recently given birth) dragged her along to various baby classes. "Give me the details," was all that she said weakly, and he obliged graciously.

"Sherlock, I'm giving you one last chance," Mycroft snapped down the phone, his voice dangerously low.

To many, that would signal instant submission, but Sherlock was not like most. "Oh, please yourself," he replied with a nonchalant air that just _screamed_ arrogant. It was all Mycroft could do to stop himself from hurling childish insults down the phone at his infuriating little brother.

He sighed loudly, and tried again, just as their mother had asked him to. "Will you not listen to reason? With John out of the picture, and Moriarty supposedly back in, it's vital that you treat this matter with your upmost attention, Sherlock. England will not be able to afford you messing about. This is a serious threat."

Indignant, Sherlock retorted, "John's not out of the picture. Don't be so dramatic. It's just a baby. What difference will it make?"

His brother sighed. Of course John would be Sherlock's priority. "You forget, little brother," Mycroft said darkly, using one hand to lean against his umbrella while the other balanced the phone precariously, "that babies are more than just the squalling, puking messes that we see them as. They hold some kind of sentiment over these people. And once they come along, things change, _priorities_ change. John won't have time helping you with your cases now that he's a father. He'll have nappies to change, I assume."

Rolling his eyes, Sherlock threw the contents of his latest experiment (following a hypothesis that involved blood clotting) onto his table before asking, "And how would you know? You're hardly an expert on such matters."

"Privileges of being an older brother, I suppose," he sniffed.

Sherlock smiled. "I see," he mused carefully, always grateful when locating another one of his brother's, as Magnussen would call it, pressure points. "So what do you propose I do then?"

"Find a new John."

Her next job was to meet a certain Mycroft Holmes and determine the facts for herself. Fith was still confused, and wondered if she had finally cracked when she recollected the events of last night. Having excused herself from her family- who were cheerfully planning their next day trip, equipped with matching shirts and all- with the excuse of baby-sitting, (thanks again, Gwen), she started to make her descent into Central London where, as Mycroft had told her, there would be a car to pick her up.

She knew that this was crazy, and that she would probably get herself killed, but it was all part of a new scheme that she held, one that followed the concept of Carpe Diem, of all things. Well, this, and the huge sum of money Mycroft had offered her in return for her service, much to her shock: goodbye student loans and all, it seemed. It also helped that Fith was not walking into any trap defenceless. With the help of a good friend, Fith had managed to get herself a tube of pepper spray disguised as lipstick, which she now held in her coat pocket, ready to be used at any given moment.

Fith certainly was many things, but unprepared was not one of them.

Worried that she was late, she felt reassured when a good-looking black car pulled up besides her at the very location Mycroft had stated for a number of reasons. It helped not to miss the only opportunity she had for work, (it had been a while, trust her), and to pay off her all her other loans. Also, it was on time, and that helped comfort her. After all, what kind of evil drug smuggling team of slavers would be punctual? Right? And could they afford such a sweet car? Fith didn't think so.

Sensing her uneasiness, the window was rolled down. Knowing it was pointless, but doing it nevertheless, Fith voiced these concerns to the woman she saw sat in the back of the car. Her reaction, a strong dirty look, was to be expected. "No," the woman said exasperatedly, "we're not a group of 'evil drug smuggling slavers', and yes, this is a nice car. Please climb in. Mycroft is waiting for you. He's not known for his patience."

Indicating her apprehension with a small nod of her head, Fith opened the door, took a deep a breath, and then climbed in. It wasn't until she was sat beside the woman- who was texting with a vehement pace- and the car was hurtling down the street did Fith realise that no one knew what she was doing or where she was going.

 _Carpe diem, my ass_ , she thought to herself, now distressed.

Mycroft was not a patient man, and so at the prospect of having to wait for a dolt of a being, he was, admittedly, irked. He had a country to run. Time literally meant money. It was only the cigarette in one hand that kept him from voicing these opinions down the phone to Fith. Getting her number was child's work; sometimes Mycroft thought he was wasted in this route with his exceptional skills, but these thoughts would often pass quickly, especially after remembering his own experience of undercover work when he had to save Sherlock that time. Better here, he decided with a certain kind of satisfaction.

"She's here," a voice called out, interrupting his line of thoughts. Looking up, Mycroft nodded, folded his newspaper, and stood up, reaching for his beloved umbrella: it held a kind of intimidation, he thought, and so it always went with him for these kinds of introductions, or for meetings with his little brother.

The girl, Mycroft noted, was taller than he had first imagined- Russell and his band of _nerds_ , or whatever it was that people called them these days, had warned him that webcams could prove unreliable- but she still looked small enough compared to the grand spacious room he had her taken to. Again, better intimidation, he thought.

She was unable to stand still, instead spinning around on the spot, trying to take in the situation. It looked more like a warehouse than an office, which was making her feel increasingly uneasy.

Noticing this, he called out, "It's nice, isn't it?" causing her to spin on her feet, apparently alarmed.

"There's no need to look so worried," he continued, slowly walking towards her, "I can assure you that my intentions are strictly professional."

She didn't look any less worried at that, although she nodded slowly, as if taking his words in. "You wanted to see me." It was more of a statement than a question, and Mycroft found himself nodding.

"Yes, if I remember quite correctly. But I should first offer you a warning." Seeing her expression stiffen, he added, "It's all necessary formalities, don't worry. Since this is a matter of the government's concern, it's even more important that we go through this."

Fith nodded.

"You are not to repeat any of the following to anyone, not even your family."

"But-"

" _Nobody_." He gave her a firm look. "If you should do so, I will know about it, and believe me, I won't be happy."

She shook her head this time. "But why?" she asked, frowning from confusion. "And what would you do if I did?"

He sighed, and gave the umbrella in his grip a small twirl. "Well obviously we wouldn't have you killed. There are rules against that, it would seem. No, no, we would simply have to _remove_ the information from you, and whoever it is you blabber to." Noticing that she still looked somewhat bewildered, he rolled his eyes and said, "I'd have to plant certain devices that would force some form of amnesia to affect you and whoever else is involved. It would certainly remove this small piece of information, but it would also remove most of your memories. Believe me, this is not the first time I've made, and acted on, that threat."

Fith just gulped heavily at that and nodded. "I won't tell anyone, I swear."

Mycroft smiled coldly. "I'm pleased to hear that. You're certainly easier to control than the last man who came in here."

She didn't know whether that was a good thing, and so thought it best to just leave it.

"Oh," he said suddenly, making her jump. "Forgive me. Where are my manners today? I haven't offered you a seat-"

"There's no need," she said quickly, interrupting him, "let's just get on with it."

He inclined his head, watching her carefully.

"You said you wanted me to take part in some kind of espi- whatever you call it. But why? I mean, surely you have an entire team of, you know, agents or what not at your disposal to be used."

"Is it espionage that you're referring to?" Feeling a headache coming on, Mycroft began to rub at his temples regretfully. "I have a proposal for you: how about you listen while I explain the situation to you. It might prove easier for the both of us. Then- and only when I've finished- you can ask me as many questions as you like, within reason of course."

Since Fith thought this perfectly reasonable, she agreed, saying, "alright then."

At this, Mycroft's expression grew sterner, if that was even possible. With a dramatic move of his umbrella, he asked her, "Have you ever heard of a certain Sherlock Holmes?"

The name rang a bell in Fith's head. "I recognise it, I think. But I don't know who he is." Having suddenly clocked on, she asked, "Wait, isn't that your name too? Mycroft _Holmes_."

He exhaled laboriously, as if her words exhausted him. "It's true, I have the burden of being his brother," he admitted darkly. Fith looked puzzled at this, but went along and inclined her head, gesturing for him to continue. "I don't suppose then that you've heard of James Moriarty?"

Again- even though she wasn't too confident about who he was- Fith thought that she recognised his name, and voiced this to Mycroft, who stared at her with a look of pure bafflement.

"Do you ever read the news?" He asked her, all the while trying to soothe his aching head.

Fith shrugged in response to his scornful remark. "It makes me sad," was her only defence, which didn't go down very well.

Shaking his head, Mycroft said, "That is something which you will have to change. Sherlock, I should warn you, despises being in the company of ' _ignorant_ ' people."

Fith would have protested- after all, she wasn't going to stick around if he would insult her so- but Mycroft had other plans, and was already continuing his small speech.

"There's an easy way to resolve this. I'll send you all the relevant files concerning both Sherlock and Moriarty, which should help keep you updated with who it is you will be dealing with. For the sake of all this, you will read them carefully. After all, it will prove most useful since they have all the information that you will need to know."

"So wait, let me get this straight," she said, gesturing for him to stop talking, which he did. "You want me to spy on your- what- _brother?_ "

Not quite understanding what it was about this that puzzled her so, he cleared his throat and said, "Well yes, I suppose so."

Fith stared at him, astonished. "But I thought this was all for the government?"

"Oh, it is," he reassured her. "Since his involvement in the murder of Magnussen, I've been advised- in exchange for keeping him at home- to keep an eye on-"

"He's a murderer? You want me to spy on a _murderer?_ "

"I wouldn't call him that, necessarily. Perhaps on a more formal note-"

"But you're telling me that he killed a man?"

Mycroft, having reached the tip of his patience, nodded with particular emphasis. "Yes, and I can assure you that, having read his file, you will know everything it is that confuses you." Sensing her discontent at being told off so, he thought he would try and compliment her in the hope of settling things a bit. "But, admittedly, we have been trying to keep such news away from being known by the public, so I suppose it's not your fault that you didn't know; not if it hasn't been in the news. But again, you will find out all of this, and more, once you've read his files. Carrying on, he's now helping us to solve the matter concerning-"

"He killed a man, and now you're letting him _help_ you?"

Mycroft gave her a pointed look. "I've organised everything that has to do with the matter of his rehabilitation. All areas of the course of action has been sorted. There's no need for you to worry. He's a valuable asset to our cause, and in no way a danger to the public. As I've said many times before, sometimes we need-"

"And you want me to spy on him?"

Being interrupted clearly bothered him. "Partly. I also want you to monitor his behaviour and, in a way, look after him. When he was given leave to go after Moriarty, he was unknowingly given an ultimatum, organised by me, of course: he was to be watched over and regulated. Now, since we lack the usual trust that comes with most sibling relationships, I've had to look elsewhere. His usual partner, John- who will be mentioned in the files- is unable to be by his side persistently. It seems having a baby changes one's priorities," he wrinkled his nose in obvious distaste. "So, once again, I've had to look further. I need someone who can stay by his faithfully day and night."

"He owns a flat. Now frankly, I find it distasteful but he's absolutely charmed by it, refusing to move somewhere closer to me, or even cheaper. As you can imagine, the rent is more than he can afford, what with its prime location, which is made all the more difficult by his recurring drug habit-"

"What?"

"-Not now. Again, it's all in the file. What matters is that I have persuaded him into looking for a potential flatmate who can help him cover the costs of the rent. While he hasn't necessarily agreed to this, we can, with certain changes, persuade him to interview several people. One of those will be you. You will do whatever it takes to be accepted. Now, Sherlock will perhaps not agree with this statement but he loves an audience, even if he dislikes people generally. All you would have to do is stay interested, and avoid falling into his expectations of 'conventional' people."

This was a lot to take in. The conversation was moving swiftly, and Fith wished that she could obtain some kind of transcript to help her understand better. "Firstly, how?" She asked, running a hand desperately through her hair, before adding, "And why me?"

Looking at her as though it was simple, Mycroft said, "You're a graduate of the Royal Academy of Dramatic Art, are you not?"

Where the bloody hell did he get that kind of information from? She voiced this with a real heated sense of indignation. "Wait? How do you know about that?"

"If I remember correctly from your file, it says that you passed with flying colours."

"My file?" She asked, raising her eyebrows. "You went through my- And what do you _mean_ 'flying colours'? Where did you get that from?"

Ignoring her, Mycroft continued. "If I remember correctly," He began with a look of pure concentration, "you were never picked up by the various agents and casting directors that habited the place, despite your skill. Why is that, I wonder?"

This seemingly hit a nerve for Fith, whose anger died down only to be replaced with a sense of shame. "I don't know," she finally said, having remained silent for a bit, "it was supposed to be inevitable that someone was interested, but they never were-"

"That's good enough for me," Mycroft told her with his usual lack of tact. "If you are to succeed with this then you're going to have to be the very best."

Shaking her head, Fith closed her eyes. "But maybe I'm not good enough. You've said it yourself, no one wanted me."

"You're unknown, which is useful," Mycroft explained. "But you will be good by the time I've finished preparing you. My brother insists that he can deduce anything correctly, but we're about to change that. He cannot know the truth or I will have lost my power over him, and breaking the pact made with fellow members of authority could force them to change their mind, and therefore the overall decision. I should warn you, while I'm not overly fond of my brother, I won't have his life put in danger."

"From what I know of you so far, I can tell that he would despise you. It's no insult to you-" He added, having seen her disgruntled expression, "-he just dislikes most conventional people. You would have to interest his curiosity, confuse him with your actions, but then draw him to a point where he can tolerate your presence, while taking care that he doesn't deduct anything more than we want him to. It's not an easy task, I must warn you."

"Now, as for what's in it for you, I can assure you that the flat, though I've made it sound unpleasant, is rather agreeable to most. The location is prime, and it's spacious. Haven't you been wanting to move out for a while now?"

"I-" She froze. "How did you know that?"

"I've been there before. I know the signs." He told her with a grim smile. "Then there's the subject of money. You would, of course, be paid monthly for your services. A fair amount, if I may say so myself."

Narrowing her eyes, Fith asked "How much?" in a tone as indifferent as she could manage, while in reality, she felt the exact opposite.

When he revealed the amount he had in mind, Fith found her jaw dropping unwillingly. It was the kind of sum that she could only ever dream of, and even then that only counted as her monthly wages.

"Yes," he said with a knowing smile. "I thought that would do nicely."

"What about my family? What do I tell them?"

Fidgeting with his umbrella, he looked back up at her. "You will lie, of course. Tell them some elaborate story about a new job, or something." With a malicious look, he added, "You could even tell them that Sherlock is your, er, _partner._ "

She frowned, shaking her head. "I already have a boyfriend. They'd know I was lying."

"I don't care." And he really didn't, "That's your problem at the end of the day. What does matter to me is that you give me your consent. Will you do this?"

It wasn't a difficult choice to make. A flat of her own (well, technically), a good, (no, screw that, _incredible_ ) wage, and the idea of having an important job was enough to make her nod politely, and say, "I suppose this could work out, yes," while screaming, ' _yes, yes, oh god, yes,'_ on the inside.

"Good," He said, offering her the contract and a pen. "I'll be contacting you with this phone," he held out a new looking BlackBerry, which she quickly pocketed, "so don't lose it. You'll also be updated regularly on the plan of action; so keep looking out for any news. I hope I don't need to remind you to read up on those files again. Do your research. And don't tell _anybody_."


End file.
